Selective hydrogenation of conjugated diolefines to monoolefines



3,009,969 SELECTIVE-'HYDROGENATION F CONJUGATED .DIOLEFINES TO MONOOLEFINES Michael Staines Spencer and-Dennis Albert'Dowden, both of vNorton-on-Tees, England, assignors to Imperial Chemical Industries Limited, London, England, a corporation of Great Britain No Drawing. Filed Dec.'14, 1959., SerJNo. 859,145 Claims priority, application Great BritainDec. 17,1958 .14 Claims. (Cl. 260-666) This invention relates to theiselective hydrogenation of United States Patent-C olefines, for example the hydrogenation of .bntadiene t0 butenes. In thehydrogenation of conjugated olefines, it,is.-diflicult to terminate the reaction at the production of the mono-olefines. Thus, in the hydrogenation of butadiene it is diificult to produce butenes Without, at the same time, producing substantial quantities of n-butane.

The present invention provides a process in which butadiene and other conjugated olefines may be converted to the corresponding monoolefines without the production of substantial quantities of saturated hydrocarbons.

Thus, according to the present invention there is ,provided a process for the hydrogenation of conjugated olefines to mono-olefines without the formation of undesirable quantities offurther hydrogenation products, which comprises the step of contacting a solution containing [Co( CN) ions with a conjugated olefine in "the presence of hydrogen.

It-is believed the solution containing [Co(CN) 1 ions rnay-containtheseionsinequilibrium'with V 2(QN)10] -ions-according*to the equation: zrcommarer ozrcuilue .ol'efine by shaking undera "that thetco tCNliul ions maybe reduced withithe hydrogen employed to give [HCo'(CN') 3- ions racgqrdr ing o the equation:

and thatgthe hydrogenation-bearing*EHC0(CN) 51 ions may thenreact 'with'thecon ugated olefine, for example, 'butadiene, according to the equation:

,cobalt complex.

outthe-processof the-present; invention it I i product obtained. When the starting rnaterialis.butae diene, the use of a (CN)-:Co molar ratioofwthefirder of 5:1, gives rise to a .progluct, rich in ;tr-ans-butene-2 whereas-the useof a;(QN)7; Corn1olar ratio of the order 7 of 10:,l;.gives rise .to a productprich in ,butene-l.

h p oc ss i thepr sentinvention may betoperatea over afairly widete perature -rang e, tor example 0. .C;.

to 100? ,C., but is; preferably operated.inthewicinity of room temperature forexamplefio" -C ..-o1- below,,,.and the reactants are not allowed to come into contactrwithrair, otherwisehundesirable-oigidationtakes place.

Elevated pressures, for exampleup. to .100. atmospheres may be. used. 1 r g The reaction may be carried out inaqueous solutionor butadiene volume ratio was 3:1.

Patented Nov. 21, 1961 v i 2, v, intthe presence of,an:alcohol*-watermixture, such asya methano1 water= mixture or;

. .Whemgaseous hydrocarbons, such as .butadiene, rare temp :ployedjit. is desirable to'contact the. solution containing ZLCQ(CN)\5]3 I,1ODS with hydrogen togive hydrogen-bear:- ;ing.ions. therein-and then topass the-hydrocarbon in admixtureawithhydrogen through the solution containing the hydrogen-bearing ions. These steps may.conveniently be carried; out, for-example, in "a' vertical column. It is desirablefor '{the quantity "of 'hydrogenin; the gaseous mixture to be greaterthan*that'required stoichiometrically. It has been found thatexcess "hydrogen may 'con veniently beprovided' by using 'two"vertically disposed columns in series down which.:the solution is passed in counter-current fiow to separate hydrogen supplies. to "each column, the hydrogen .supplyto "the lower column being replaced by the mixture of the gaseoushydrocarbon "andhydi ogenlafter an initialpurging period. '.It willjbe understood thatthe solution mayfbe continuously recycled desired, Alternatively, the solution containing hydrogen-bearing ions maYIbe'contacted withagaseous gasflmixture of the hydrocarbon and hydrogen.

[When using a liquid hydrocarbon such as cyclopentadiene, this may be added to the solution .containing'hydrogen-bearing ions and themixture submitted to constant shaking under 'a' hydrogen. atmosphere. 'The. liquid hydrocarbon may however beadded to the solution containing [Co(CN) ions and thernixture then subjected t a yd o n a mosp I The invention isillustrated by the following examples.

Example 1 internal diameter of 4 cm. was packed with Raschig rings and the column was purged with hydrogen. Small vol- .umes of the solutions were. addedalternately tothecolumn until addition was complete and hydrogen was then bubbled through; theliquid. hydrogen-butadieneimixil re thereafter; passed upwards through.v the column. Analyses of samples of the inlet and outletjgases were carried out-by means of a mass spectrometer. The 'following results were obtained:

Hg C4Ho CtHa 4 10 :;Example 2.v -A catalyst solution, having a volume"of50 ml. and containing 2.6 gm. of potassium cyanide and 0.95 gm. of cobalt chloride, CoCl -6H O, was contained in a ml. flask. The (CN)-:Co molar ratio was 10:1. Hydrogen was introduced 'over the liquid, the pressure being 1 atm. absolute, and the flask was ,shaken. 31 ml. of gaseous hydrogen were absorbed. The hydrogen was then replaced by a hydrogen-butadiene mixture in which the hydrogen: Theliquid was again shaken 'and the :gas uptake was 100 ml. Asample of the gas remaining abovethe liquid in the flask'was analysed by gas chromatography and was found to-havethetollowing. composition:

Butene-l 40.5% by volume. Trans-butene-Z 3.8% by volume. .Cis-butene-Z,i..;. u 0.9% byhyolume. Bntadiene v i 'Not detected. n? --."-.'I,-' l In of fi y erohwater mixture.

, 3. Example 3 Example 2 was repeated, using, however, a catalyst solution containing 1.3 of potassium cyanidev and 0.95 gm. of cobalt chloride in '50 ml. of water. This catalyst had a (CN)-:Co molar ratio of 5: 1. The reduction and reaction were carried out as before, the hydrogen absorption during the reduction step being 31 ml. and the gas uptake of the hydrogen-butadiene mixture during the reaction step being 174 ml. On analysis the residual gas was found to have the following composition:

Butene-l 5.8% by volume. Trans-butene-Z 39.5% by volume. Cis-buteneZ 1.1% by volume. Butadiene Not detected. n-Butane Do.

Example 4 Two solutions were prepared, one containing 15.2 gm. cobalt chloride, CoCl .6H O, in 200 ml. water and the other containing 41.6 gm. potassiumcyanide in 200-ml. water. Two glass columns (each 50 cm. high and 4 cm. diameten rinternal dimensions) were packed with Raschig rings, joined vertically and purged with hydrogen. The two solutions were mixed in the columns, the resulting catalyst solution, having a (CN)" :Co molar ratio of :1, was passed down the columns consecutively and recycled. continuously at about 10 litres per hour by a pump. The hydrogen supply to the lower column was then replaced by a butadieue/ hydrogen mixture at a flow rate of 5 litres per hour. Analyses of samples of the inlet gas to and the outlet gas from the lower column were carried out by gas chromatography or a mass spectrometer. The following results were obtained:

The exitgas from the upper column through which hydrogen alone was passed contained 4.5% butenes and 0.3% butadiene.

The temperature during the carrying out of the above Y four examples was about 20 C.

Example 5 Example 4 was repeated except that the catalyst solution contained 19.5 gm. cobalt chloride and 26.6 gm. 3

potassium cyanide in 500 ml. water, giving a (CN)" :Co molar ratio of 5 :1. A heating coil was inserted. in the circulating system and the mean temperature of the columns was about 50 C. :The following results were 7 obtained.

7 Upper Column Lower Column Inlet. Outlet Inlet Outlet 1 99:9 97.5 80.5 87.0 butadiene-.. 0 0 19.4 9.2 0 0.4 0 0.5 0 1.9 0 3.2 0 0.2 0 0 d 0 0 0 v0 Exam - Example '4 was repeated except that the catalyst solution contained 19.5 cobalt chloride and 53.2 gm. potassium cyanide in 500 water, the solution was cooled and the mean temperature of the columns was 7 C. The following results were obtained:

Example 4 Was repeated'except that the catalyst solution was heated to 60 C. The following results were obtained:

Upper Column Lower Column Inlet Outlet Inlet Outlet 96. 5 81. 0 84. 5 0 0 18. 9 13.4 0.1 1. 2 trans-buteneZ. 0 3.1 0 0. 4 cis-butene-2 0 0. 1 n-butane 0 0 0 0 Example 8 52 gm. potassium cyanide were sealed into a glass tube and put, together with a solution of 19.0 gm. cobalt chloride in 500 ml. water and some steel balls (to break the tube), into an autoclave of 1100 ml. capacity. 'Aiter three purges with hydrogen the autoclave was evaucated and 55 gm. butadiene expanded in from a weighed cylinder. It was then brought to 100 C. and hydrogen admitted, first to 50 atm. and then to 100 atm. total pressure. .An uptake of 39 atm. was observed. When the pressure was released samples were taken of the exit gas and analysed by gas chromatography with the following results:

Hydrogen 18.5%.

Butadiene 16.9%.

Butene-l 30.2%.

Trans-butene-Z 19.6%.

Cis-butene-Z 14.2%.

n-Butane None detected.

Example 9 A catalyst solution having a volumeof 50 ml. and containing 1.3 gm. of potassium'cyanide and 0.95 gm. of cobalt chloride, CoCl .6H O, was contained in a 100 flask. The (CN)-:Co molar ratio was 5:1. To this solution 5 ml. of cyclopentadiene monomer were added and hydrogen, at a pressure of ,1 atm. absolute, was introduced over the liquid mixture. The hydrogen was continuously absorbed and was stopped after an uptake of 470ml. The temperature was 20 C.

Analysis of the gas above the liquid by means of a mass spectrometer showed hydrogen, cyclopentadiene and cyclopentene only.

We claim:

l. A process for the hydrogenation of conjugated diolefines to mono-olefines without the formation of undesirable quantities of further hydrogenation products, which comprises the step of'oontacting a catalyst solution prepared by mixing an aqueous solution of a soluble salt of divalent cobalt with a solution of an alkali metal cyanide with a conjugated di-olefine in"the' presence of hydrogen. I

2. A process as claimed in claim'l when operated at a temperature in the range of 0 C. to 100 C. v a

3. Aprocess as claimed in claim 2 in which the temperature is about 20 C.

4. A process as claimed in claim 1 when operated at a pressure in the range of 1 to 100 atmospheres.

5. A process as claimed in claim 1 when carried out in an aqueous solution.

6. A process as claimed in claim 1 when carried out in an alcohol-water mixture.

7. A process as claimed in claim 1 in which the catalyst solution is contacted with hydrogen to give hydrogenbearing ions therein before being contacted with a conjugated di-olefine.

8. A process as claimed in claim 7 in which the diolefine is gaseous and is passed, in admixture with hydrogen, through the solution containing hydrogen-bearing 10115.

9. A process as claimed in claim 8 in which the quantity of hydrogen in the gaseous mixture is greater than that stoichiometrically required.

10. A process as claimed in claim 7 in which the solution containing hydrogen-bearing ions is contacted with a gaseous di-olefine by shaking under a gas mixture of the hydrocarbon and hydrogen.

11. A process as claimed in claim 7 in which the solution containing hydrogen-bearing ions is contacted with a liquid di-olefine by adding the di-olefine to the solution and submitting the mixture to a constant shaking under a hydrogen atmosphere.

12. A process as claimed in claim 1 in which the catalyst solution is contacted with a liquid di-olefine by adding the hydrocarbon to the solution and subjecting the mixture to a hydrogen atmosphere.

13. A continuous process for the hydrogenation of conjugated di-olefines to mono-olefines in the gaseous phase which comprises the steps of passing a solution prepared by mixing an aqueous solution of a soluble sat of divalent cobalt with an aqueous solution of an alkali metal cyanide through two successive contact zones, contacting the solution counter-currently in the first zone with hydrogen and in the second zone with a gaseous mixture comprising hydrogen and the di-olefine to be hydrogenated, collecting gaseous mixtures comprising at least one monoolefine from each contact zone, and collecting the solution from the second zone and returning it to the first zone.

14. A process as claimed in claim 1 in which the molar ratio of cyanide to cobalt in said catalyst solution is at least 5:1.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A PROCESS FOR THE HYDROGENATION OF CONJUGATED DIOLEFINES TO MONO-OLEFINES WITHOUT THE FORMATION OF UNDESIRABLE QUANTITIES OF FURTHER HYDROGENATION PRODUCTS, WHICH COMPRISES THE STEP OF CONTACTING A CATALYST SOLUTION PREPARED BY MIXING AN AQUEOUS SOLUTION OF A SOLUBLE SALT OF DIVALENT COBALT WITH A SOLUTION OF AN ALKALI METAL CYANIDE WITH A CONJUGATED DI-OLEFINE IN THE PRESENCE OF HYDROGEN. 